If you want to actually import 3D models, you’ll need 3D Invigorator Pro by Zaxwerks. Note that you need the Pro version. AE itself cannot handle 3D objects.
I believe the usual workflow is to model, animate and render in Blender (or whatever other 3D software you use) and use AE for final 2D compositing. Blender is a great software, but like all 3D apps it requires serious investment in learning how to use it.
A mid-level between those options is to import cameras and lights from the 3D software into AE, relying on AE’s “2.5D” capabilities (navigation in 3D space without actually working with 3D objects). This could be tricky with Blender. It is commonly stated that Cinema4D has the best integration with AE in this respect.
Hope this helps,
AA (a Softimage|XSI fan!)